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Compact or Triple Crank?

limewave2011-08-10 00:13:29 +0000 #1
Anybody riding mountain bike with a compact crank? If so, do you like it more or less than a triple and why? What are you gaining with the compact and what are you compromising?

I'm asking b/c the bikeshop guy just told me all xc racing is moving towards compact and that's what he recommended on my new bike. But I have never ever ridden compact on my xc bike. I'm a little nervous about it.
Veronica2011-08-10 00:20:18 +0000 #2
I have a triple on my mtb, so take this with a grain of salt...

But I'd think about it the same way I did for my road bikes. What gear ratios do I need for my riding? Can I get something close with a compact? If I could, then I'd go with the compact.

Veronica
SheFly2011-08-10 00:27:29 +0000 #3
I haven't heard of a compact for MTBs...

That said, I only use a double anyway. In most of our races/terrain here, there is no need for a "big ring". I find I can ride most anything, including a recent "dirt road crit" with just the double. This also provides more clearance for me with logs and rocks.

Like V said, think of the gears you will use. A triple is likely unnecessary (I take that back if you live in CA and are MTB riding in the hills!).

SheFly
limewave2011-08-10 01:26:49 +0000 #4
I have no understanding of gearing. The numbers mean nothing to me--I just don't speak that language. I just go by how things feel. Maybe you guys can shed some light for me.

Right now I have a 9-speed

22-34-44 with 11-32 in the rear

What I'm lookin' at:

20/47 front

12-36 on the back.
Veronica2011-08-10 00:41:01 +0000 #5
Quote:

Originally Posted by SheFly

(I take that back if you live in CA and are MTB riding in the hills!).

SheFly

Yeah, I don't think I could give up my little ring on my mtb. I think I spend 90% of every ride in it.

Veronica
jessmarimba2011-08-10 02:02:59 +0000 #6
I know the bf seriously dislikes the idea of 2x10 gearing for mtb. In his opinion, it's moving that way because that's what companies are making, and not b/c that's what people really want. But I'm sure it depends on where you're riding (and who you ask - but he's been riding for eons, so it's not like he's not in bike shape).

Personally, I wanted to go 1x9 before I got hurt and lost most of my leg strength. I was spending the majority of every ride in the same 2-3 gears. But...now I'm very happy with a triple
bellissima2011-08-10 00:36:24 +0000 #7
limewave, are you sure is a 20/47? it seems like a very odd number, most double cranks ( what you call compact) start at 24 for the small ring and go up to 44 for the big ring. A size 47 will be too big on a mountain bike. A 20 teeth granny gear would be super easy (too easy) and a 47 would be too hard. Using a double really depends on the area you ride and you level of fitness. Here in SoCal most of the fast racers are using doubles and really like them, but you must consider that they don't use the granny gear at all so having it make no sense and they tend to ride bigger gears anyways.
laura*2011-08-10 02:06:09 +0000 #8
Quote:

Originally Posted by bellissima

limewave, are you sure is a 20/47?

I think she typoed: The El Mariachi specs say 27-40.

I wouldn't apply the term "compact" to any of the mountain doubles. If anything, they are the opposite of compact. Here are three types of mountain double:

1) A 22-32-44 crankset with the 44 tooth ring removed (and possibly replaced with a bash guard).

2) Like above, but with the middle ring replaced by a larger ring at the factory - perhaps 22-36.

3) True doubles meant for use with wide range 10 speed cassettes. SRAM seems to like the ratios 26-39 and 28-42. The FSA crank on the El Mariachi splits the difference at 27-40.

---

In the 2000-oughts, the MTB industry settled on a 22-32-44 crank with a 9 speed 11-34 (or 11-32 for flat landers) cassette as optimal. The problem is that a lot of gear ratios are duplicated. There might only be 13 distinct ratios.

With the change to 10 speed cassettes, it is possible to provide nearly the same lowest to highest range while eliminating many duplicates by using 2x10 gearing. I'm not sold on this though - this change does lose the lowest and highest gears!

I think SRAM has a (old) patent on cranks with 1:1.5 ratio chainrings. They found that this jump provides for smooth easy quick shifting. (26 times 1.5 is 39!) This wasn't useful until the 10 speed generation 'cause the 1.5 ratio is just a bit too big for narrower range cassettes.

Shimano's DynaSys ratios also claims better shifting than before.

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The 3x9's lowest gear (22:34) is gone from the 2x10 system. The 3x9's next lowest gear (22:30) is almost the same as the 2x10's lowest gear (26:36).

At the other end, the 3x9's highest gear (44:11) is also gone from the 2x10 system. The 3x9's next highest gear (44:13) is comparable to the 2x10's highest gear (39:11).

And of course, those of us who are thrilled to use a 29er 36 tooth 9-speed cassette to provide an even lower gear on a 26er - well, we're left out in the cold.

---

Do you need the extremes of gear ratios? Do you need to zoom down a highway to get to a monster climb?

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